1. Field of the Invention
This invention relates to improvements in boat lifts. More particularly, it concerns novel boat lifts of the cradle type that are associated with some form of permanent berth, e.g., a dock, finger pier, seawall, or the like.
2. Description of the Prior Art
A variety of different types of boat lifts have been developed to handle various kinds of boats in different ways and locations. In a broad sense, these may be divided into mobile lifts that can lift and move boats about on land or water and permanent lifts designed to lift boats at a fixed location. This present invention relates to lifts of the second class.
The permanent location type boat lifts, particularly those designed to handle pleasure boats of modest size, e.g., boats of up to 40 feet in length and displacement up to 10,000 lbs., can be divided into two general classes, namely, (a) davit types which lift boats by cables that attach to some portion of the superstructure of the boat and (b) cradle types which lift boats by engagement of the hull of the boat from its underside once the boat has entered the berth at the permanent lift location. This invention relates to the cradle type boat lifts.
Cradle type lifts can be further subdivided into (1) ramp types in which a lift cradle moves in and out of the water on stationary ramps that extend into the water at the berth and (2) cable types in which a lift cradle is hoisted in and out of the water by cables that suspend from supports positioned at the berth above the waters. This invention relates to the cable hoist cradle boat lifts.
A number of improvements have been proposed for the cable hoist cradle boat lifts as illustrated by U.S. Pat. Nos. 2,709,345; 3,077,742; 3,265,024 and 4,329,082. However, two shortcomings have persisted with prior known lifts of this class, namely, use of extensive superstructures to support the cable systems and undesirbly high loadings imposed on the cables and their support systems. The present invention offers solutions to these problems and additional improvements in cable hoist cradle type boat lifts.